1. Field of the Invention
This invention relates to a recoil starter used as a starting system for engines, and more particularly to a recoil starter adapted to reduce a peak load at the engine starting time and lessen the influence exerted on the hand, and also a recoil starter having a dust-proofing effect.
2. Description of the Prior Art
In general, this type of recoil starter is provided with a case housing therein a series of mechanisms formed of a reel which has a rope capable of being drawn out and taken up freely, and which is rewound by a spiral spring, and ratchets extended and retracted via inhibit plates; and adapted to be driven by engaging the ratchets with a starting pulley connected directly to an engine. In general, in this type of recoil starter, the hand directly feels the starting torque of the engine through the rope, so that the hand receives shocks. Moreover, very few devices for preventing the entry of dust from a circumference of a shaft into the interior of the recoil starter are provided for structural reasons.
Under the circumstances, the applicant of the present invention previously proposed a recoil starter (Japanese Utility Model Laid-Open No. 190862/1987) formed so as to prevent dust from entering an engine, by connecting a clutch mechanism of the recoil starter and a spiral spring together, and a rope and a reel together by a shaft respectively, forming a bearing, which support these shafts, in a starter case so as to be integral therewith, and providing a seal member in the vicinity of the shaft, and a recoil starters (Japanese Utility Model Laid-Open Nos. 61575/1988 and 92078/1988) formed so as to seal a clutch mechanism and an engine by fixing to a crank case a starter case having a bearing portion extending around an axis of a crankshaft; providing the clutch mechanism on of the crankshaft side of the bearing portion; providing a reel on an outer side of the other starter case; and providing a seal member on a sliding part of an outer circumferential section of the bearing portion, i.e., measures to prevent dust from entering the engine were already taken.
However, in all of the above-mentioned related art recoil starters, the hand directly feels the starting torque of the engine through the rope, so that a peak load (a load imparted to the recoil starter when a piston moves over a compression upper dead center) at the time of an engine starting operation is high. Therefore, a shock due to this load is directly transmitted to the hand and arm to cause an undesirable effect to be produced. Moreover, the measures to prevent the entry of dust into the recoil starter were not substantially taken.
The present invention has been made in view of these circumstances, and provides a recoil starter capable of solving the problems encountered in the related art recoil starter, reducing a peak load on the recoil starter at the time of an engine starting operation, and lessening a shock given to the hand and arm, and resistant to dust including sand and litter.
According to an aspect of the present invention, the recoil starter is formed of a starter case having a bearing portion extending around an axis of a crankshaft; a starter shaft passed through the bearing portion and adapted to be turned; a one-way clutch mechanism formed between one end portion of the starter shaft, which extends from the bearing portion to the crankshaft, and an engine; a starter case united with the first-mentioned starter case and having a bearing portion supporting the other end portion of the starter shaft; a reel mounted on the portion of the starter shaft which is between the two bearing portions so that the reel can be turned with respect to the starter shaft; a rope wound in a groove of the reel; a spiral spring urged in the direction in which the rope fixed at both end portions thereof to the first-mentioned starter case and reel is taken up; and a spiral spring fixed at both end portions thereof to the reel and starter shaft and adapted to transmit with an elastic action a rotational force of the reel, which occurs when the rope is drawn out, to the starter shaft, a dust seal being provided in the bearing portion provided so as to extend around the axis of the crankshaft.
A related art recoil starter has a transmission line of force of ropexe2x86x92clutch mechanismxe2x86x92engine. On the other hand, in the recoil starter according to the present invention, the shaft is made rotatable to form a transmission line of force of ropexe2x86x92reelxe2x86x92spiral springxe2x86x92shaftxe2x86x92engine, and the spiral spring having an elastic action is interposed between the shaft and reel so that a peak load at the time of an engine starting operation is absorbed in this spiral spring. Furthermore, the dust seal is provided in the bearing portion provided so as to extend around the axis of the crankshaft.